1. Field of the Invention
The present invention relates generally to an enclosure adapted to receive and hold captive a printed circuit board without requiring screws and where the printed circuit board is adapted to provide strain relief for wires from the printed circuit board.
2. Description of the Related Art
Today, automation systems which include sensors are being installed in more and more buildings, including both new construction and in structures that are being renovated and/or rebuilt. The incentives for putting automation systems into a building are numerous. High on the list are occupancy sensors to help reduce costs by turning off lights when a person leaves a room, more efficient use of energy, simplified control of the building systems, ease of maintenance and for effecting changes to the buildings systems. Facility managers prefer to install systems that can interoperate amongst each other. Interoperability is defined as being able to link together different products, devices and systems for different tasks and developed by different manufacturers to form flexible, functional control networks.
An example of a typical automation system includes security systems which includes occupancy sensors and/or lighting controls, and HVAC systems, all possibly provided by different manufacturers. It would desirable if these separate disparate systems can quickly and easily be mounted to a standard wall or ceiling electrical outlet box.
Prior art systems generally comprised closed proprietary equipment supplied by a single manufacturer. With this type of proprietary system, the installation, servicing and future modifications of the component devices in the system are restricted to a single manufacturer's product offering and technical capability. In addition, it is usually very difficult or impossible to integrate new technology developed by other manufacturers. If the technology from other manufactures can be integrated, it may be too costly to consider.
Thus, it is desirable to create a system whereby individual sensors, processors and other components can be easily mounted to an outlet box. A few of the benefits of using an open system include increased number of design options for the facility manager, lower design and installation costs because the need for customized hardware is greatly reduced and system startup is quicker and simpler.
An integral part of any automation control system are the sensors and transducers used to gather data on one or more physical parameters, where one such parameter is occupancy or motion. It would be desirable if a plurality of sensor functions could be quickly and easily fitted into a standard single wall box opening and be able to be powered from and communicate with one or more control units, i.e., processing nodes on a control network.
The number and types of sensors in the device can be, but not limited to, multiple, dual or single occupancy and security sensing via means including passive infrared, ultrasonic, RF, audio or sound or active infrared. In addition, other multiple or singular transducers may be employed such as temperature sensors, relative humidity sensors, ambient light sensors, CO sensors, smoke sensors, security sensors, air flow sensors, switches, and the like.
In order to minimize the number of unique devices that are installed in a room, it is desirable to have a sensor device reliably perform as many functions as possible as this will reduce the wiring costs as well as the number of devices required to be installed on the walls of the room. Additionally, from an aesthetic point of view, architects are under increasing demand by their clients to reduce the number of unique sensor nodes in any given room.
Further, it is also desirable to have the transducers or sensors communicate with a microprocessor or microcontroller that can be used to enhance the application of the transducer and be powered by a stand alone unit which includes both the sensor and a printed circuit board which can include a power pack in a single enclosure where the printed circuit board can be quickly and easily inserted and held captive in the enclosure without requiring screws.
At the present time low voltage sensors such as occupancy sensors can be wired to a relay or dimmer panel, or to a localized power pack that houses a single load relay and generates the low voltage power for the sensor. Another option is to wire low voltage sensors to a stand alone unit which includes both the occupancy sensor and the power pack in a single enclosure. One problem with this method is that the manufacturer essentially doubles the amount of products which results in decreased economics.
Referring to FIG. 1, there is shown a prior art mounting base 20 used by many low voltage occupancy sensors. The base 20 shown in FIG. 1 mounts either to a ceiling or an electrical outlet box with screws 22 which pass through slots 24. A centrally located aperture 26 is provided to route low voltage wires. A low voltage sensor is mounted to the base 20 or back cover after the installation wiring is completed.
Referring to FIG. 2, there is shown the base 20 being attached to a 4″ octagon electrical outlet box 28 with screws 22. The cover 30 supports the sensor and is attached either to the base 20 or to the box 28 with screws after the low voltage wires 32 from the sensor are passed through the centrally located opening in the base and are connected to system wires. The wires from the sensor pass directly through the base and are connected to a printed circuit board which is mounted either in the outlet box with screws or at a remote location, also with screws or a printed circuit board holding structure. The printed circuit board is used to provide power and control connections for the occupancy sensor. Wires which are not clamped in place, particularly low voltage wires which are normally connected directly to a printed circuit board of a sensor, can easily be disconnected from the printed circuit board when subjected to a sudden tug or a sustained strain or tension.
What is needed is an enclosure adapted to receive and hold captive a printed circuit board without requiring or using screws, has a minimum number of parts and an advantage geometry and where the printed circuit board is configured to provide strain relief for wires from the printed circuit board.